Do ecosystem types tell the full biodiversity story? Potentials of ecosystem types as indicators of plant species richness

The expansion of human activities in natural areas continues to drive unprecedented biodiversity loss. Management based on ecosystem‐level assessment is replacing management focusing on individual species, with promises of offering an efficient, general framework for authorities to prioritize conservation actions to areas important for biodiversity. However, the success of the approach depends on whether ecosystem characteristics (e.g. productivity and geographical extent) reflect species‐level biodiversity patterns. Here, we investigate how ecosystem types following IUCN standards relate to species richness of vascular plants using large‐scale monitoring data from central Norway. We assess whether commonness and red‐list status of the ecosystem are associated with higher richness of the total species pool, threatened species and the number of ecosystem‐exclusive species. We also compare two nested hierarchical levels of ecosystem types in how they may help in the identification of areas with high biodiversity value based on species distributions across ecosystem types and ecosystem–occupancy relationships. Our results showed that common ecosystem types had higher regional, but not local, species richness, including exclusive and red‐listed species richness, regardless of their red‐list status. Yet, threatened ecosystem types, which tended to be rarer, had higher local and lower regional species richness than non‐threatened counterparts. As species became more common, they occupied an increasing number of ecosystem types, although this was lower than expected under random distributions. Although common major ecosystem types contained more minor ecosystem types, species occurred less in such fine‐scale ecosystem types than expected from their occurrences in coarse‐scale ecosystem types. Synthesis and applications . Our study demonstrates that the commonness and red‐list status of ecosystem types can be informative of biodiversity measures in terms of species richness at selected spatial scales. The scale‐dependence of these indicators and the inverse relationship between red‐list status and commonness illustrate that conservation strategies must consider several ecosystem characteristics to efficiently protect species of conservation concern. Furthermore, we show that fine‐scale ecosystem types represent more informative units for biodiversity measures at the species level for vascular plants, possibly because coarse‐scale ecosystem types differ more largely in their geographical extents and consequently account for community drivers at different scales.